Respirator facepieces have been made from a soft compliant material, commonly rubber, that rests against the wearer's face and forms a seal against the wearer's facial skin. The rubber typically is thick so that it can support filters and exhalation valves. See, for example, U.S. Pat. No. 2,652,828 to Matheson and U.S. Pat. No. 4,155,358 to McAlister et al. Thick rubber facepieces, however, can make the respirator heavy and uncomfortable to wear. Additionally, thick rubber adds to material and manufacturing costs. If the rubber is made thinner, however, the mask may have a tendency to collapse onto the user's face, particularly when tightening the harness while donning the respirator.
To make a facepiece lighter but not at the expense of reducing structural integrity, a thin rigid structural part has been incorporated into the facepiece. These rigid structural parts are commonly produced through injection molding and are often referred to as a “rigid insert”. The rigid insert provides adequate structure for supporting filter cartridges and valves. A soft compliant material, which conforms to a person's face, is disposed on or about the rigid insert to enable the mask to fit snugly over the wearer's nose and mouth. The use of a rigid insert in conjunction with a soft compliant portion tends to make the mask lighter and more comfortable to wear, particularly when compared to the previous masks that had used thick rubber throughout essentially the whole mask body to support the filter cartridges and valves. Masks that use a rigid insert in conjunction with a compliant face-contacting member are shown in U.S. Pat. No. 6,016,804 to Gleason et al., U.S. Pat. No. 5,592,937 to Freund, U.S. Pat. No. 5,062,421 to Burns et al., and in U.S. patent application Ser. No. 10/719,959 filed Nov. 21, 2003, entitled “Respiratory Facepiece And Method Of Making A Facepiece Using Separate Molds.”
Although masks that employ rigid inserts in conjunction with a soft compliant portion tend to be lighter and more comfortable to wear, they nonetheless can be somewhat more complicated to manufacture. Masks that use rigid inserts require multiple parts and the additional step of hermetically joining the insert to the soft, compliant, face-contacting portion. The need for these additional parts and assembly steps can add to manufacturing costs.